Primary (unprocessed) transcripts of piRNAs are transported from the nucleus to the cytosol by an unknown mechanism. Studies with Drosophila indicate that Uap56, Nxt1, Nxf2, Nup154, and Nup43 may be involved in exporting piRNA precursors from the nucleus (Zhang et al. 2012, Muerdter et al. 2013, Handler et al. 2013).